Wire ropes



J 30 1 A. DlETZ ETAL INVENTORS AL FRED DIE T2 GERHARD DIE 7'2 8) P WIREROPES Filed April 27, 1959 ATTORNEYS United States Patent 3,018,607 WIREROPES Alfred Dietz, 30 Damaschkestrasse, Neustadt, near Cohurg, Germany,and Gerhard Dietz, 190 Friedrich- Ebertstrasse, Monchroden, near Cohurg,Germany Filed Apr. 27, 1959, Ser. No. 809,209 11 Claims. (Cl. 57-148)This invention relates to wire ropes, at least the outer covers of whichare of stranded form. As a rule, such ropes have a hemp or steel corewhich may be separated from the outer strands by an intermediate layerof strands.

Wire ropes must comply with two main requirements in addition to havingsufficient mechanical strength. Firstly, there should be no crossing ofwires, for the stresses occurring when the rope is in use then rapidlylead to notching of the wires and therefore to early wear. Secondly, therope must not become unlaid when loaded without being guided, forinstance, when used on a rotary tower crane. The rope elements orstrands extend helically and therefore tend when in tension tostraighteni.e., to increasingly reduce the radius of their spiral. Inother words, the strands tend to move towards the rope axis and to comecloser to one another. Since the design of the rope makes it almostimpossible for the strands to shift in this way, the rope tends tobecome unlaid.

Many methods have been tried to reduce wire crossings and rope twist butthey have usually conflicted with other requirements. For instance, itmay well be desirable for the pitch of the inner stranded layers to begreater than the pitch of the outer layer, to ensure satisfactorystretching, but wire crossings then become almost inevitable. Wirecrossings occur to a very considerable extent in the case of strandedspiral ropes devoid of load twist, for the inner and outer strandedlayers of such ropes must be laid in opposite directions to one another.

A known proposal to obviate these difliculties is to wind a protectivelayer of flat wire around the inner stranded layer or around the ropecore, whereafter the protective layer may or may not be provided withspecial spiral ridges adapted to engage between the various strands ofthe outer stranded layer to prevent lateral contact between thelast-mentioned strands. Since the flat wire covering is relatively soft,however, the forces applied to the rope deform the same and may, ofcourse, impair the spiral ridges.

The wire rope according to this invention is devised with the sameobject of obviating wire crossings but also ensures that the unguidedrope will not become unlaid when loaded. To achieve this purpose, theinvention starts from a known rope construction comprising a core, aninner stranded layer, a protective layer thereabout and an outerstranded layer with spiral ridges engaging between the outer strands. Inthe improved rope construction according to the invention, the spiralridges are peripherally connected unyieldingly to a non-distortingprotective layer surrounding the inner stranded layer.

By proceeding in the manner according to the invention, not only is asatisfactory solution provided for the problem of wire crossings butalso a completely non-twisting rope is provided, for the outer strandswhich exert a thrust on the core when the rope is loaded can neitherdeform the protective layer nor move beyond the firm spiral ridges inthe manner required for the rope to become unlaid.

The invention can be embodied in a variety of ways. For instance, a firmprotective layer of fiat wire can be Wound around the inner strandedlayer or rope core and formed with grooves corresponding in number,helix and pitch to the outer strands. The pressing of the grooves intothe flat wire cover leads to the production between the grooves of therequired spiral ridges which extend between the outer strands. Dependingupon requirements,

3,018,607 Patented Jan. 30, 1962 the flat wire can be wound around therope core either with the same twist as the grooves or with an oppositetwist. In another very useful embodiment of the invention, the spiralridges are placed in separable manner upon the protective layer of therope core but are nonreleasably connected thereto.

Moreover, although the protective layer is usually placed between aninner and an outer stranded layer, the protective layer could be laiddirectly around the rope core. In such a case, as in the otherembodiments of the invention, a plastic protective layer with the spiralridges formed on it directly could be used instead of a metal protectivelayer.

Reference will now be made to the drawings wherein:

FIGURE 1 diagrammatically illustrates a rope according to the inventionwith some of the outer stranded layer omitted;

FIGURE 2 is a diagrammatic cross-section through the two-layer strandedspiral rope shown in FIGURE 1, and

FIGURE 3 is a diagrammatic cross-section through another embodiment ofthe invention.

In FIGURE 1, the reference 5 applies to the whole of a rope core which,in the example illustrated in FIGURE 2, comprises a core strand 6 (1+9wires), a protective layer 7 and an inner stranded layer 8. A fiat wire9 is wound around the complete structure with a relatively reduced pitchso that the whole rope core is inside a covering wound around it.

The cover 9 is formed, independently of the lay and pitch of the innerstrands 8, with grooves 10 which, in the example illustrated in FIGURE1, have an opposite lay to the lay of the strip 9 and correspond innumber, pitch and lay to the outer strands 11 stranded on the core. Theactual design of the outer layers is of no importance for the inventionand they could be individual wires, for instance, round wires or shapedwires. The outer strands 11 lie in the grooves 10 which are withadvantage given a radius of curvature adapted to the radius of curvatureof the outer strands 11.

A ridge 12 is left between adjacent grooves 10 and is so designed thattwo adjacent outer strands 11 cannot engage with one another laterallyor at least cannot notch one another when subjected to pressure.

Of course, a flat wire layer, as 9, could be provided elsewhere, forinstance, between the inner stranded layer 8 and the wires 7.Conveniently, the flat wire layer will always be applied to the ropecore or the like during the complete stranding operation and will besimultaneously formed with the grooves 10.

The example shown in FIGURE 3 is a Seales rope in which the outerstrands 13 are laid in the same direction as the inner strands 14. Thesame co-operate with a wire insert 15 to form a rope core surroundedexternally by a flat wire cover 16. Rigidly'secured thereto are spiralridges of dimensions and arrangement such as to engage between the outerstrands 13. When such a rope is pulled without being guided, the outerstrands 13 tend to press concentrically inwards, but since the core 14,15 cannot yield, the rope would become unlaid if itwere not that theouter strands, as they try to unwind from the core, abut with the spiralridges 17.

If the protective layer of the rope according to the invention consistsof a flat wire cover 17, the wire used could be, for instance, about1.0-1.2 mm. thick and about 2.0-2.5 mm. wide. As already mentioned,instead of a fiat wire cover a protective plastic layer can be usedwhich is sprayed on to the core directly and on which the requiredspiral ridges are formed.

If required, this idea could be carried further and the inner strandedlayer omitted entirely; instead, the rope core'and spiral ridges couldbe formed in unitary manner of plastic.

It is immaterial for the invention how the rope core and outer strandedlayer are disposed. The strands of the core and of the outer layer canbe stranded in the same direction using, for instance, a parallel layfor the inner strands and a cross-lay for the outer strands.Alternatively, the inner and outer strands could be stranded in oppositedirections to one another, in which case it is advantageous if the flatwire protective layer between the inner strands. and outer strands isgiven a short length of lay independently of the pitch of the ropeelements contiguous with the protective layer, since the elasticity ofthe cover is increased and therefore the cover remains closed even whenthe rope is bent considerably.

Of course, using the inventive idea ropes free from a load twist can beprovided which have relatively few outer strands and can therefore havewires of any required thickness; this step ensures that the ropes alwayshave an appropriate outer strength.

In the drawings the spiral ridges are shown as being of roughlytriangular cross-section, but other cross-sections can be used providedthat the ridges can engage appropriately between the outer strands andserve as a fixed abutment therefor to prevent the rope from becomingunlaid.

What we claim is:

1. A helical stranded wire rope comprising a core section, a protectivelayer covering and confining said core section, and an outer layer ofwire strands helically laid on said protective layer, said protectivelayer being nondeformable by strains on the rope and being formedperipherally with a series of rigid helical ridges respectively lyingbetween and holding separate the adjacent strands of said outer layer sothat no notching contact can occur between said wire strands and therope cannot untwist under strain.

2. A helical stranded wire rope comprising a core section, a protectivelayer covering and confining said core section, and an outer layer ofwire strands helically laid on said protective layer, said protectivelayer being nondeformable by strains on the rope and being formedperipherally with a series of rigid helical ridges respectively lyingbetween and holding separate the adjacent strands of said outer layer sothat no notching contact can occur between said wire strands and therope cannot twist under strain, said protective layer defining betweensaid ridges helical grooves conforming in cross-section to the curvatureof said wire strands, said wire strands being laid in said grooves.

3. A helical stranded wire rope comprising a core section, aprotectivelayer covering and confining said core section, and an outer layer ofwire strands helically laid on said protective layer, said protectivelayer being nondeformable by strains on the rope and being formedperipherally with a series of rigid helical ridges respectively lyingbetween and holding separate the adjacent strands of said outer layer sothat no notching contact can occur between said wire strands and therope cannot untwist under strain, said protective layer being formed bya flat wire wound helically on said core section and provided withintegral rigid projections which form said ridges, said flat wireforming between said ridges helical grooves corresponding in number,pitch and lay to and receiving said wire strands.

4. A wire rope as claimed in claim 3, said fiat wire being wound with apitch sutliciently small that said protective layer remains closed whenthe rope is bent.

5. A wire rope as claimed in claim 3, said fiat wire being a wire ofuniform transverse dimensions precrimped to form said projections and toprovide between said projections concavities which form said grooves.

6. A wire rope as claimed in claim 3, said flat wire being wound in thedirection of the twist of said ridges.

7. A wire rope as claimed in claim 3, said flat wire being wound in adirection opposite to the direction of the twist of said ridges.

8. A helical stranded wire rope comprising a rope core, an inner layerof strands helically laid on said core, a protective layer covering andconfining said inner layer of strands, and an outer layer of wirestrands helical- 1y laid on said protective layer, said protective layerbeing non-deformable by strains on the rope and being formedperipherally with a series of rigid helical ridges espectively lyingbetween and holding separate the adjacent strands of said outer layer sothat no notching contact can occur between said wire strands and therope cannot untwist under strain.

9. A helical stranded wire rope comprising a rope core, an inner layerof strands helically laid on said core, a protective layer covering andconfining said inner layer of strands, and an outer layer of wirestrands helically laid on said protective layer, said protective layerbeing non-deformable by strains on the rope and being formedperipherally with a series of rigid helical ridges respectively lyingbetween and holding separate the adjacent strands of said outer layer sothat no notching contact can occur between said wire strands and therope cannot untwist under strain, said protective layer being formed bya fiat wire of uniform transverse dimensions wound helically on saidinner layer of strands, said wire being precrimped to provideprojections forming said ridges and, between said projections,concavities forming between said ridges helical grooves receiving saidwire strands, the strands of said inner layer lying respectively inhelical channels at the inner side of said protective layer oppositesaid ridges.

10. A wire rope as claimed in claim 9, said flat wire being wound in adirection opposite to the direction of the twist of said ridges and witha pitch sufiiciently small that said protective layer remains closedwhen the rope is bent.

11. A helical stranded wire rope comprising a rope core, an inner layerof strands helically laid on said core, a protective layer covering andconfining said inner layer of strands, and an outer layer of wirestrands helically laid on said protective layer, said protective layerbeing non-deformable by strains on the rope and being [formedperipherally with a series of rigid helical ridges respectively lyingbetween and holding separate the adjacent strands of said outer layer sothat no notching contact can occur between said wire strands and therope cannot untwist under strain, said protective layer being formed bya flat wire helically wound on said inner layer of strands, said flatwire having rigidly secured to its outer side rigid projections whichform said ridges.

References Cited in the file of this patent UNITED STATES PATENTS1,405,835 Green Feb. 7, 1922 1,405,837 Green Feb. 7, 1922 1,699,174Whittemore Jan. 15, 1929 2,074,956 Carstarphen Mar. 23, 1937

